Apparatus for showering molten metals



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s. E.` WOODS APPARATUS FOR SHOWERING MOLTEN METALS Filed Jan.

Oct. 7, 1952 Patented Oct. 7, 1952 APPARATUS FOR SHOWERING MOLTEN i METALSa Stephen Esslemont Woods, Bristol, England, as-

signor to The National Smelting Company Limited,^London, England Application January, 24, 1950, seriaNo. 140.281 i InGreat. Britain February` %1949 `9 Claims.

This invention .relates to apnaratus for showering a molten metal, of the type disclosed in Patents 23517544 and 2,473304, comprising a chamber containing a pool of the liquid metal and a mechanically operated element,. such as ta rotor hearing vanes, buckets, corrugations or a helical i surfaee,.o`r an oscill'ating paddle or the 1ike,`en-

.closed in the chamber and dipping into the molten metal.

such an apparatus may be used` for the condensation of metale,` such as zine, by means of the shower orspray of moltenmetal, which, may

therefore conveniently be" referred to in this context as the "coolanti' i In anapparatus of this kind means must be p ovided .for scaling the gland's in the chamber through, which the rotary or oscillating motiontransmtting shaft'of the rotor or other showeri ing. element passes.

Methods hitherto proposed .and used for scaling such glarids have made useeoi devices intended to prevent liquidmetal rrom reaching the glands. In one example the shaft is provided with sleeves .designedto catch and deflect back into the cham- 'ber any liquid metal splashed on them or on, the

shaftwith which they are assoeiated.` In another proposal a slow stream of gas. is forced through the glands from theexterior to the; in-

terier of the chamber.

` Methods hitherto employecLsuch ras those mentionedi above,- have y not been entirelysatisfactory. The above-mentioned sleeveshave failed to pre- `lyerit thepermeation or passageof metallic vapor or; liquid from` the interier of the ehamber and liquid metal hasbeen foundto solidify upon the working surface of the gland. When .cold gas i from the exterior has been forced i through the ;gland with` a substantiallyi unimpeded annular clearance therebetween means for feedingxliquid metal` to one end of the clearance toiclose the clearance and means for collecting the liquid metal escaping from :the other end i of the clearance.

The sleeve may be made of silicon carbide or 3 graphite.

Preferably the clearance is wider at the end to which liquid metal is fed and narrower at the end from. which it escapes back to the chamber. i i

The. invention will be further described with reference. to the embodiments shown n the ccompanying drawings. i

Fi'gure 1 is a vertical section of a splash condenser embodying a horizontal rotor;

Figure 2 isaivertical section of a splash condense' embodying a vertical rotor.` i

`Figura 3 is` asection on the line 3-3 of Fig- In theembodiment shown in Figure 1 the rotor I is. carred by a water cooled metal shaft 2. Where the, shaftpasses through'the side walls' 3 of the condenser a sleeveA of graphite or silicon i carbideis cemented to the shaft, Secured in the side walls 3 surrounding the sleeves 4 are gland rings 5`n which the sleeves are a looset fit, the inside` of' the gland ring tapering towards the outside of.. the condenser. Thus at the inner wall: of the condenser there may be a clearance of one inch which tapers to a quarter inch at the outside.

The shaft 2 itself may be of ironor steel and maybe hollow enabling it to be water-cooled. The rotor I" itself maybe of graphite, silicon carbide or other suitable r'efractory material and be keyed to a cement sleeve surrounding the shaftQto which it is keyed by splines formed on the shaft. The cement sleeve preferably extends into the gland 5 andsupport the sleeve thereof, which may be heyedto the cement sleeve in the 'same way. as the rotorand may be formed integral With the rotor, ifthe latter is of the same material as the sleeve. The shaft is rotatably supportedin external bearings 8. e

Liquid metal is.fed't0 the inner end of the clearance between the sleeve 4 and gland 5 by splash .action alone and escapes from the outer endof the glandto the etrough 6, returningto the interior of the condenser through a drowned opening 1. i

` Possible alternative materials to silimanite for the. ring or gland. are silicon carbide or fused alumina butthelatter is -not recommendedwhen Zinc isthe liquid metalowing to the possibility oil reaction toorm zinc aluminate. The main requirement' for an alternative material is that the` material be a `refractory which does not containironin a form liableto catalyze the decemposition of carbon monoxide and cause deposition of carbon, since in the majority of the applicatons envisaged the gas in the chamber is largely composed of carbon monoxide. Fireclay may be used although it contains iron, provided it is well fired at a high temperature, when its iron content becomes inactive as a catalyst for decomposing carbon monoxide.

In the embodiment of Figures 2 and 3 the condensing chamber is laterally defined by four walls, H, !2, !3 and M. In the centre of the roof !5 is a square opening !6 bounded on the sides by four walls of which two are denoted by ll and s. Except for a circular portion in the centre, the bottom of this opening is defined by a ledge marked IS. Through the hole defined by the ledge 19 passes a shaft 20, covered by a sleeve 2| of silicon carbide or graphite, which carries the rotor 22. A refractory gland ring 23 extends down from the rim of the ledge IS. At a level just above that of the ledge !9 are two refractory troughs, 24 and 25, extending along two of the side walls, ll and !2 respectively, of'

the condenser. At right-angles to and connected with the centre of trough 24 is a trough 26 which leads through an opening zl in the wall H. Similarly trough 25 is connected by trough 28 to an opening 29 in wall l8. Some of the metal splashed up by the rotor zz falls into troughs 2 1 and and by this means is conducted to the ledge !9 where it forms a reservoir for feeding metal down through the gland which is the space 39 between the sleeve 2| and the gland ring 23. water which is introduced through pipe 3l.

When the apparatus is started up liquid metal fioWs freely through the gland and keeps it sealed, but after a' time the flow may cease, the gland clearance having .become choked with a solid deposit. i a deposit consisting mainly of zinc oxide is for-med and acts in the manner of a line or bushing, on which the silicon carbide sleeve carriedlby the shaft rubs but with little friction, the gland clearance being completely filled by the deposit.

If the liquid metal is lead the flow is continuous, little or no deposit being formed and the gland clearance being filled and sealed with liquid metal. In this case application of heat to the gland by means of convenientlyplaced burners 9 is advisable in order to maintain the fluidity of the' metal fiowing through the gland.

The clearance tapering in the direction of .flow of the liquid metal enables a continuous flow of liquid metal through the gland 'to be maintained, i

or. a coherent mass of solid deposit to form in the gland and act as a bushing providing an effective seal, while permitting the shaft to rotate freely.

I claim:

1. An apparatus for showering a molten metal comprising a chamber containing a pool of the liquid metal, a mechanically operated metal showering element enclosed in the chamber and dipping into the molten metal, a wall of the chamber, a shaft for Operating said element which shaft is supported outside the chamber and extends through an aperture in the wall of the chamber to make connection with the element, a sleeve fixed to the shaft, said sleeve being of material selected from the group consisting of silicon carbide. and graphite, a gland of refractory material which does not 'contain iron in a form liable to catalyze the decomposition of carbon monoxide and cause deposition Theshaft 20 of the rotcr is cooled. by`

When the liquid metal is Zinc, such 4. An apparatus for showering a molten metal comprising a chamber containing a pool of the liquid metal, a mechanically operated metal showering element enclosed in the chamber and dipping into the molten metal, a Wall of the chamber a shaft for Operating said element, which shaft is supported outside the chamber and extends through an aperture in the wall of the chamber with a substantially unimpeded annular clearance therebetween to make connection with the element, said metal showering element feeding liquid metal from the chamber to one end of the clearance to close the clearance and flow metal therethrough, and means for collecting the liquid metal escaping from'the other end of the clearance.

5. A gland scaling arrangement for a metal showering apparatus comprising a gland, a shaft passing through the gland with a substantially unimpeded annularclearance therebetween, metal showering means secured to the shaft which feed liquid metal to one end of the clearance to close the clearance and flow metal therethrough, and means for collecting thenliquid metal escaping from the other end of the clearance, said shaft being rotatably mounted in an external hearing.

6. An arrangement as claimed in claim 5 in which the clearance 'is wider at the end to which liquid metal is fed than at the end from which it escapes.

7. An arrangement as claimed in claim 6 in which the clearance tapers.

8. An arrangement as claimed in claim 5 comprising means for heating the gland.

9. A gland sealing arrangement for a metal showering apparatus comprising a gland, a Vertical shaft passing through the gland with a clearance therebetween, a reservoir for eeding metal down through the gland, metal showering means Secured to the shaft, and a tro gh for collecting part of the metal showered by the metal showering means and conducting it to the reservoir.

STEPHEN ESSLEMONT WOODS.

REFERENCES CITED The following references are of record in the file of this patent:

- UNITED STATES PATENTS Robson Junen, 1949 

